Active control of a read/write head

ABSTRACT

The invention generally relates to hard disk drives with a disk and a read/write head, and methods for preventing contact between the disk and the read/write head. The hard disk drive includes a z-axis actuator configured to control movement of the read/write head, and to prevent contact between the read/write head and the disk, based on signals from a controller that indicate when the distance between the read/write head and the disk are outside a predetermined range, such as between 0 and 10.0 nm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. Nonprovisional application Ser. No.15/848,685, filed Dec. 20, 2017 (now U.S. Pat. No. 10,304,492), which isa continuation of U.S. Nonprovisional application Ser. No. 15/621,593,filed Jun. 13, 2017 (now U.S. Pat. No. 9,881,644), which is acontinuation of U.S. Nonprovisional application Ser. No. 15/405,738,filed Jan. 13, 2017 (now U.S. Pat. No. 9,734,864), which is acontinuation of U.S. Nonprovisional application Ser. No. 15/194,833,filed Jun. 28, 2016 (now U.S. Pat. No. 9,666,229), which claims thebenefit of, and priority to, U.S. Provisional Application Ser. No.62/295,681, filed Feb. 16, 2016. The entirety of the contents of each ofthese applications is incorporated herein by reference.

FIELD

The present disclosure relates generally to magnetic data storagesystems and devices, and, more particularly, to a system for achievingreduced head-media spacing (HMS) in a hard disk drive (HDD) by providingactive control over positioning of a read/write head relative to arotating magnetic data recording and reading surface of a disk.

BACKGROUND

A hard disk drive (HDD), also referred to as a “hard disk”, a “harddrive” or “fixed disk”, is a data storage device used for storing andretrieving digital information using one or more rapidly rotating disksor platters coated with magnetic material. The platters are paired withmagnetic heads arranged on a moving actuator arm. The magnetic heads areconfigured to read and write data to the disk surfaces. When an HDD isin operation, each disk is rapidly rotated by a spindle system and datais read from and/or written to a disk using one or more read/write headspositioned over a specific location of the disk by the actuator.

A read/write head uses a magnetic field to read data from and write datato the surface of a disk. As a magnetic dipole field decreases rapidlywith distance from a magnetic pole, the distance between a read/writehead and the surface of the disk must be tightly controlled. Currentsystems attempt to control head-media spacing or separation (HMS)between the head and disk surface so as to maintain head as close aspossible to a rotating disk for effective operation of the HDD. As usedherein, HMS generally refers to the total distance between theread/write head and the disk surface. HMS may include, for example, notonly the flying height of the read/write head relative to the disksurface, but also thicknesses of all coating or lubrication layers oneither of the read/write head or disk surface.

The HMS between a head and disk surface is a critical factor fordetermining the amount of information that can be written to and/or readfrom a disk, sometimes referred to as an areal bit density (number ofbits/unit area on a disk surface). For example, as the separationbetween the head and the surface of the disk increases, theeffectiveness of both reading data from and writing to the diskdecreases. Thus, a larger HMS between the head and disk surface requireslarger bit cells, thereby resulting in smaller areal density forrecorded information. Conversely, a smaller HMS between the head anddisk allows for smaller bit cells, thereby allowing for greater arealdensity for information recording. Increasing the areal densityincreases the total storage capacity of the disk drive, while decreasingthe areal density decreases the total storage capacity.

There are existing systems that attempt to control the flying height ofthe read/write head so as to decrease the HMS for improving theoperation of the HDD and increasing storage capacity. For example, somedisk drives rely on an air bearing surface (ABS) configuration, whereinthe separation between the read/write head and the disk is maintained asthe result of the balance between the aerodynamic lift provided by thefast moving air generated by a disk's rotation, and the down forceapplied to a slider holding the head by the load beam portion of theactuator arm.

A further refinement to the ABS design is referred to as a thermalflying height control (TFC) design. In a TFC design, the slider includesan electrical resistor placed near the magnetic transducer of the headand, when activated, produces a temperature rise near the transducercausing the transducer to protrude towards the disk surface. Althoughthe general flying height of the slider remains unchanged by the TFC,the magnetic transducer is brought even closer to the disk surface byseveral nanometers. When power to the heater is reduced or terminated,the heat quickly dissipates to the rest of the slider and the protrusionretracts. The cycle of heating and cooling can be repeated thousands oftimes per second. Although a TFC design allows for subtle movement ofthe head closer to the disk surface by a few nanometers, the TFC designrelies on the flexible load beam and the ABS design, which generallyacts over a range of hundreds of nanometers in the z-direction from thehead to the disk surface.

Current systems and designs for controlling HMS between the read/writehead and disk surface have shortcomings and thus impact overallperformance of the HDD. For example, the ABS design fails to fullyprevent contact between the head and disk surface during operation ofthe HDD. In particular, as part of the ABS design, the head area of theslider is gently urged toward the disk until contact is made(“touchdown”), at which point the slider is urged away from the disk(“pull-back”). Contact between the head and disk surface may also occurdue to internal and external vibrations directly to the HDD, as well asthe fluttering of the disk that may occur as a result of fluctuations inair flow within the HDD. The act of contacting the disk causesmechanical wear of the head which, over time, often leads to operationaldegradation and eventually failure. In order to guard against potentialdamage from intermittent contact with one another, the disk surfaces aregenerally coated with at least two layers; a first hard coating and asecond lubricant coating. In addition, the heads themselves may also becoated with a hard coating to provide additional protection. Althoughthe hard coatings and lubricant layers may provide protection, they alsoincrease the HMS between the head and disk surface, thereby presenting achallenge when attempting to reduce HMS values and limiting the abilityto increase areal densities for improving reading and storagecapabilities.

Another drawback of the ABS design is the turbulence within the HDD as aresult of high-speed air generated by the rotation of the disk. The airturbulence causes a “windage” effect, which can result in diskfluttering, as well as slight movement of the actuator arm, both ofwhich can result in the head missing a desired track on the disksurface, commonly referred to as track miss-registration (TMR). Thus,TMR further reduces the reliability and performance of an HDD.

SUMMARY

The demand for higher areal densities in hard HDDs has been consistentlyincreasing, as higher areal density allows for increased storagecapacity of a disk and further improves data reading from the disk. Thepresent invention relates to a system for achieving higher arealdensities by providing reduced head-media spacing or separation (HMS).In particular, the system of the present disclosure is configured tomonitor the position of a read/write head relative to a disk surface andactively control positioning of the read/write head within a relativelytight HMS tolerance (e.g., between 1.0 nm and 10.0 nm, and, in someinstances, 4.3 nm) between the head and disk surface while ensuringcontact between the head and disk surface is prevented.

The system of the present disclosure replaces the conventional ABSdesign with a fully active actuator assembly including a z-axis actuatorconfigured to support and move a read/write head in a directionsubstantially orthogonal relative to the disk surface. In other words,the z-axis actuator is configured to move the read/write head in az-direction towards or away from the disk surface. The z-direction issubstantially parallel to a z-axis oriented substantially orthogonal tothe disk surface. The z-axis may generally be parallel to the axis ofrotation of the disk.

The system includes a controller configured to monitor the HMS betweenthe read/write head relative to the disk surface and transmit controlsignals to the z-axis actuator to cause movement of the read/write headin the event that the read/write head is positioned outside of a desiredHMS range of values. In particular, the controller may be configured toreceive and process measurement data, including one or more measurementsof a flying height of the read/write head relative to the disk surfaceduring disk rotation. Based on the measurement data, the controller maybe configured to determine the position of the read/write head andwhether the position of the read/write head falls outside of a set HMSrange of values. Thus, the controller may be referred to herein as a“servo controller”, in that the controller is a servomechanism utilizingerror-sensing negative feedback to correct the performance of amechanism (e.g., adjust the position of the read/write head).Accordingly, the system of the present disclosure is configured toactively control the flying height of the head above the disk surface atall times, thereby ensuring that the head remains within a desired HMSrange during operation while also ensuring that the head never makescontact with the disk surface.

The system of the present disclosure provides numerous advantages. Forexample, by providing fully active control over a z-axis actuator andensuring that contact between the read/write head and disk surface neveroccurs, the protective hard coating and lubrication layers customarilyapplied to the disk and head surfaces can be eliminated, or, at the veryleast, the disk and read/write head surfaces may include a significantlysmall amount of hard coating or lubrication layer (e.g., coating orlayer having a thickness in the range of 0.1 nm to 2.0 nm). Theelimination of, or reduction in the thickness of, such layers results ina significant reduction in the HMS between the head and disk surface,thereby allowing for increased areal density to be achieved.Additionally, since all physical contact between the head and the disksurface is eliminated, a HDD incorporating the system of the presentdisclosure will have reduced wear and tear and have a much longeroperating life than current hard disk drive units.

Additionally, because the system does not rely on an ABS design, airwithin the HDD is no longer required as the actuator design of thepresent invention does not rely on aerodynamic forces to maintain theflying height of the head. Accordingly, a low air pressure environment,including a zero, or near-zero, air pressure may be maintained withinthe HDD enclosure, thereby eliminating substantially all aerodynamicdrag and turbulence that are major causes of head and disk surfacecontact, disk flutter, TMR, and power consumption. Additionally, oralternatively, in some embodiments, any oxygen remaining within the HDDenclosure may be purged and replaced with an inert gas, such as nitrogenor helium, which may improve the longevity and operation of componentswithin the HDD enclosure. For example, typical HDDs may include oxygenwithin the enclosure, which can lead to oxidation of the HDD componentswhich may affect performance and reliability. Accordingly, purging theHDD enclosure of oxygen and replacing with an inert gas prevent HDDcomponents from being exposed to oxygen.

Another advantage of eliminating the ABS design relates to the fact thatthe read/write heads consistent with the present disclosure do notrequire air bearing sliders, which can be the single-most expensivecomponent of an HDD due to the time-intensive manufacturing processesand costs involved. Air bearing sliders are generally made from aluminumoxide/titanium carbide (Al₂O₃/TiC), as this material is ideal for makingsliders with smooth faces and sharp edges. However, such material isincompatible with most common semi-conductor manufacturing processesand, as a result, these manufacturing processes must be altered toaccommodate the aluminum oxide/titanium carbide material, which is timeintensive and results a loss of usable space on the substrate. Thesystem of the present invention allows for the manufacture of headsusing a silicon (Si) substrate from a Si wafer, wherein such a materialis much more compatible with most common semi-conductor manufacturingprocesses and equipment. The system allows for large gains in magnetichead manufacturing efficiencies to be obtained by reducing the size ofthe head and increasing the number of heads that can be produced on anygiven Si substrate in that the Si wafer has a size of approximately 300mm, which is much greater than a typical 200 mm size of an Al₂O₃/TiCwafer. Thus, there are no lower limits on physical dimensions of aceramic substrate for thin film transducers for use on the read/writehead consistent with the present disclosure. Furthermore, by using aSi-based thin-film head, additional electronic circuitry and componentsmay be added for improving performance, such as, for example, apre-amplifier circuit for boosting the read/write head signal prior totransmission of the signal over a longer distance to a drive interface.

In one aspect, the invention includes a system for providing reducedhead-media spacing (HMS) in a hard disk drive (HDD). The system includesa disk having a magnetic data recording and reading surface and aread/write head having a magnetic transducer configured to read datafrom or write data to the magnetic surface of the disk. The systemfurther includes a z-axis actuator coupled to the read/write head andconfigured to control movement of the read/write head in a substantiallyorthogonal direction relative to the surface of the disk. The systemfurther includes a servo controller in electrical communication with thez-axis actuator and configured to monitor positioning of the read/writehead relative to the disk surface during rotation of the disk. The servocontroller is configured to cause the z-axis actuator to adjust aposition of the read/write head to prevent HMS between the magnetictransducer and the magnetic data recording and reading surface fromfalling below approximately 1.0 nm and exceeding approximately 10.0 nm.

In some embodiments, the servo controller may be configured to monitorand adjust positioning of the read/write head relative to the disksurface during rotation of the disk to ensure that the magnetictransducer never makes physical contact with the disk surface.

In some embodiments, the servo controller is configured to cause thez-axis actuator to adjust a position of the read/write head to preventthe HMS from exceeding approximately 8.0 nm and falling belowapproximately 4.0 nm. In some embodiments, the servo controller isconfigured to maintain a position of the read/write head relative to thedisk surface during rotation of the disk such that the HMS isapproximately 4.3 nm.

The servo controller may be configured to receive and processmeasurement data including one or more measurements of a flying heightof the magnetic transducer of the read/write head relative to the disksurface during disk rotation. The servo controller may be configured todetermine whether the magnetic transducer is positioned within the HMSrange of approximately 1.0 nm to approximately 10.0 nm based on theprocessing of the measurement data. In the event that it is determinedthat the magnetic transducer is positioned outside of the HMS range, theservo controller is configured to transmit a control signal to thez-axis actuator to cause movement of the read/write head to position themagnetic transducer within the HMS range.

The processing of the measurement data may include a comparison of themeasurement data with a set of reference data comprising the HMS range.In the event that it is determined that the magnetic transducer ispositioned below the minimum value of the HMS range, the control signalcauses the z-axis actuator to move of the read/write head in directionaway from the disk surface to position the magnetic transducer withinthe HMS range. In the event that it is determined that the magnetictransducer is positioned above the maximum value of the HMS range, thecontrol signal causes the z-axis actuator to move the read/write head indirection towards the disk surface to position the magnetic transducerwithin the HMS range.

In some embodiments, the read/write head may be configured to measurethe flying height via a capacitive coupling arrangement between theread/write head and the disk surface. In other embodiments, the z-axisactuator may further include a measurement sensor configured to measurethe flying height distance. The measurement sensor may include, forexample, a capacitive coupling device.

In some embodiments, the disk, the actuator assembly, and the servocontroller are configured to operate in a low air pressure environmentwithin a HDD. For example, in some embodiments, the disk, the actuatorassembly, and the servo controller are configured to operate in a zeroor near-zero air pressure environment within the HDD. In someembodiments, the system may further include a vacuum pump configured tomaintain a zero or near-zero air pressure environment within the HDD.

In some embodiments, the read/write head may include a silicon (Si)substrate configured for supporting the magnetic transducer. The Sisubstrate may be configured to support one or more active electroniccomponents configured to be coupled to, or in communication with, themagnetic transducer. For example, in one embodiment, the one or moreactive electronic components may include a pre-amplifier positioned onthe Si substrate and in communication with a read element of themagnetic transducer. The pre-amplifier is configured to amplify readsignals from the read element of the magnetic transducer. The readelement of the magnetic transducer may include one or more inductiveelements. Additionally, or alternatively, the Si substrate may include asensor for measuring the HMS, such as, for example, a capacitivecoupling circuit. Additionally, or alternative, the one or more activeelectronic components on the Si substrate may include one or moreportions of the servo controller itself.

In some embodiments, the magnetic data recording and reading surface ofthe disk is devoid of any overcoat or lubricant layers. In someembodiments, the magnetic transducer of the read/write head is devoid ofany overcoat or lubricant layers. Yet still, in other embodiments, boththe disk surface and magnetic transducer are devoid of any overcoat orlubricant layers.

In some embodiments, the z-axis actuator may include a rigid frameincluding an elongate body having a first end, an opposing second end,and a channel extending between the first and second ends and a headassembly positioned within the rigid frame and configured to control theflying height of the magnetic transducer of the read/write head relativeto the disk surface during disk rotation. The head assembly may includean electromechanical member positioned within the channel and adjacentto the first end of the elongate body of the frame. Theelectromechanical member may be configured to receive the control signalfrom the servo controller to cause the electromechanical member tocontract and expand along a length of the channel. The head assembly mayfurther include a suspension arm positioned within the channel betweenthe electromechanical member and the second end of the elongate body ofthe frame.

The suspension arm may include a deformable portion configured totransition between a substantially planar configuration and a buckledconfiguration in response to associated contraction and expansion of theadjacent electromechanical member. When in the buckled configuration,the deformable portion generally extends in a direction away from theremainder of the first suspension arm and the frame. The read/write headis coupled to the deformable portion of the suspension arm. Thus, upontransition of the deformable portion from the planar configuration tothe buckled configuration, the read/write head is configured to move ina substantially orthogonal direction away from the suspension arm andthe frame and towards the data reading and recording surface of thedisk. When the deformable portion transitions from the buckledconfiguration to the planar configuration, the read/write head isconfigured to move in a substantially orthogonal direction away from thedata reading and recording surface of the disk and towards thesuspension arm and the frame.

The deformable portion of the suspension arm may include a shape memorymaterial having a default, substantially planar shape, and may beconfigured to bend in an outward direction upon linear force appliedthereto from the electromechanical member when electromechanical memberexpands and return to the default, substantially planar shape uponremoval of the linear force when the electromechanical member contracts.

In other embodiments, the z-axis actuator may include a rigid framecomprising an elongate body having a first end, an opposing second end,and a channel along a length thereof and an electromechanical memberpositioned within the channel and adjacent to the first end of theelongate body of the frame. The electromechanical member may beconfigured to receive the control signal from the servo controller tocause the electromechanical member to contract and expand along a lengthof the channel. The z-axis actuator may further include an L-shapedsuspension arm having a short segment and a long segment having adistal-most end upon which the read/write head is coupled. The shortsegment may be directly coupled to a portion of the frame via a notchedportion and positioned adjacent to the electromechanical member. Thesuspension arm may be configured to transition between a substantiallyplanar configuration and a bent configuration in response to associatedcontraction and expansion of the adjacent electromechanical member. Whenin the bent configuration, the suspension arm is bent at the notchedportion of the short segment and the distal-most end of the long segmentextends in a direction away from the frame. Accordingly, upon transitionof the suspension arm from the planar configuration to the bentconfiguration, the read/write head is configured to move in a directionaway from the frame and towards the data reading and recording surfaceof the disk. When the suspension arm transitions from the bentconfiguration to the planar configuration, the read/write head isconfigured to move in a direction away from the data reading andrecording surface of the disk and towards the frame.

The notched portion is arranged so as to prevent the suspension arm frombending inwardly and permit the suspension arm to only bend in anoutward direction upon linear force applied thereto from theelectromechanical member when electromechanical member expands.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the claimed subject matter will be apparentfrom the following detailed description of embodiments consistenttherewith, which description should be considered with reference to theaccompanying drawings, wherein:

FIG. 1 is a exploded view of an exemplary embodiment of a hard diskdrive (HDD) in which a system consistent with the present disclosure maybe incorporated;

FIG. 2 is a block diagram illustrating a system consistent with thepresent disclosure and configured to be incorporated into the HDD ofFIG. 1;

FIG. 3 is a flow diagram illustrating one embodiment of a method formonitoring and actively controlling the position of a read/write headrelative to a disk surface using a system consistent with the presentdisclosure;

FIGS. 4A and 4B are perspective and side views of one embodiment of ahead assembly of a z-axis actuator compatible with the system of FIG. 2illustrating a portion of the head assembly in a substantially planarconfiguration;

FIGS. 5A and 5B are perspective and side views of the head assembly ofFIGS. 4A and 4B in a buckled configuration illustrating movement of theread/write head towards a disk surface for reducing HMS between theread/write head and disk surface;

FIG. 6 is a side view of a dual head assembly including the headassembly of FIGS. 4A and 4B in a dual-design configuration;

FIG. 7 is a side view of the dual head assembly of FIG. 6 positionedbetween two adjacent disks and illustrating one of the head assembliesin a buckled configuration; and

FIGS. 8A and 8B are side views of another embodiment of a head assemblyof a z-axis actuator compatible with the system of FIG. 2 illustratingtransitioning of a portion of the head assembly from substantiallyplanar configuration to a bent configuration for movement of aread/write head towards a disk surface for reducing HMS between theread/write head and disk surface.

For a thorough understanding of the present disclosure, reference shouldbe made to the following detailed description, including the appendedclaims, in connection with the above-described drawings. Although thepresent disclosure is described in connection with exemplaryembodiments, the disclosure is not intended to be limited to thespecific forms set forth herein. It is understood that various omissionsand substitutions of equivalents are contemplated as circumstances maysuggest or render expedient.

DETAILED DESCRIPTION

By way of overview, the present disclosure is generally directed to asystem for providing reduced head-media spacing (HMS) in a hard diskdrive (HDD) to achieve increased areal bit density for improved datatransfer (e.g., reading and writing of data). In particular, the systemof the present disclosure is configured to monitor the position of aread/write head relative to a disk surface and actively controlpositioning of the read/write head within a relatively tight HMStolerance (e.g., between 1.0 nm and 10.0 nm, and, in some instances, 4.3nm) between the head and disk surface while ensuring contact between thehead and disk surface is prevented.

As used herein, “HMS” generally refers to the total distance between theread/write head and the disk surface. Accordingly, HMS may include, forexample, not only the flying height of the read/write head relative tothe disk surface, but also thicknesses of all coating or lubricationlayers on either of the read/write head or disk surface. As will bedescribed in greater detail herein, the system of the present disclosureallows for read/write heads and disk surfaces to be bare (e.g., devoidof any hard coating or lubrication layers). Accordingly, in someembodiments, the HMS between the read/write head and disk surface of asystem consistent with the present disclosure may generally refer to thedistance between a bare magnetic transducer of the read/write head andthe bare magnetic data recording and reading surface of the disk. Itshould be noted, however, that in some embodiments, the disk andread/write head surfaces may include a significantly small amount ofhard coating or lubrication layer (e.g., coating or layer having athickness in the range of 0.1 nm to 2.0 nm). Thus, HMS includes thedistance between the magnetic transducer of the read/write head and thedisk surface including any thin hard coating or lubrication layerincluded on either the magnetic transducer or disk surface.

The system of the present disclosure replaces the conventional ABSdesign with a fully active actuator assembly including a z-axis actuatorconfigured to support and move a read/write head in a directionsubstantially orthogonal relative to the disk surface. In other words,the z-axis actuator is configured to move the read/write head in az-direction towards or away from the disk surface. The z-direction issubstantially parallel to a z-axis oriented substantially orthogonal tothe disk surface. The z-axis may generally be parallel to the axis ofrotation of the disk.

The system includes a controller configured to monitor the HMS betweenthe read/write head relative to the disk surface and transmit controlsignals to the z-axis actuator to cause movement of the read/write headin the event that the read/write head is positioned outside of a desiredHMS range of values. In particular, the controller may be configured toreceive and process measurement data, including one or more measurementsof a flying height of the read/write head relative to the disk surfaceduring disk rotation. Based on the measurement data, the controller maybe configured to determine the position of the read/write head andwhether the position of the read/write head falls outside of a set HMSrange of values. Thus, the controller may be referred to herein as a“servo controller”, in that the controller is a servomechanism utilizingerror-sensing negative feedback to correct the performance of amechanism (e.g., adjust the position of the read/write head).Accordingly, the system of the present disclosure is configured toactively control the flying height of the head above the disk surface atall times, thereby ensuring that the head remains within a desired HMSrange during operation while also ensuring that the head never makescontact with the disk surface.

The system of the present disclosure provides numerous advantages. Forexample, by providing fully active control over a z-axis actuator andensuring that contact between the read/write head and disk surface neveroccurs, the protective hard coating and lubrication layers customarilyapplied to the disk and head surfaces can be eliminated, or, at the veryleast, the disk and read/write head surfaces may include a significantlysmall amount of hard coating or lubrication layer (e.g., coating orlayer having a thickness in the range of 0.1 nm to 2.0 nm). Theelimination of, or reduction in the thickness of, such layers results ina significant reduction in the HMS between the head and disk surface,thereby allowing for increased areal density to be achieved.Additionally, since all physical contact between the head and the disksurface is eliminated, a HDD incorporating the system of the presentdisclosure will have reduced wear and tear and have a much longeroperating life than current hard disk drive units.

Additionally, because the system does not rely on an ABS design, airwithin the HDD is no longer required as the actuator design of thepresent invention does not rely on aerodynamic forces to maintain theflying height of the head. Accordingly, a low air pressure environment,including a zero, or near-zero, air pressure may be maintained withinthe HDD enclosure, thereby eliminating substantially all aerodynamicdrag and turbulence that are major causes of head and disk surfacecontact, disk flutter, TMR, and power consumption. Additionally, oralternatively, in some embodiments, any oxygen remaining within the HDDenclosure may be purged and replaced with an inert gas, such as nitrogenor helium, which may improve the longevity and operation of componentswithin the HDD enclosure. For example, typical HDDs may include oxygenwithin the enclosure, which can lead to oxidation of the HDD componentswhich may affect performance and reliability. Accordingly, purging theHDD enclosure of oxygen and replacing with an inert gas prevent HDDcomponents from being exposed to oxygen.

Another advantage of eliminating the ABS design relates to the fact thatthe read/write heads consistent with the present disclosure do notrequire air bearing sliders, which can be the single-most expensivecomponent of an HDD due to the time-intensive manufacturing processesand costs involved. The system of the present invention allows for themanufacture of heads using a silicon (Si) substrate from a Si wafer,wherein such a material is much more compatible with most commonsemi-conductor manufacturing processes and equipment. The system allowsfor large gains in magnetic head manufacturing efficiencies to beobtained by reducing the size of the head and increasing the number ofheads that can be produced on any given Si substrate. Furthermore, byusing a Si-based thin-film head, additional electronic circuitry andcomponents may be added for improving performance, such as, for example,a pre-amplifier circuit for boosting the read/write head signal prior totransmission of the signal over a longer distance to a drive interface.

FIG. 1 is an exploded view of an exemplary embodiment of a hard diskdrive (HDD) 10 in which a system consistent with the present disclosuremay be implemented. The HDD 10 includes base or chassis 12 upon whichcomponents described herein may be positioned and fixed thereto, as wellas a cover 14 configured to be fastened to the chassis 12 for coveringand protecting components within the HDD 10. As will be described ingreater detail herein, the chassis 12 and cover 14 may be hermeticallysealed to one another via any known technique (e.g., adhesive, polymerstrip or gasket, etc.) in that the interior of the HDD 10 provides a lowair pressure environment, which may include a zero, or near-zero, airpressure environment.

The HDD 10 generally includes a spindle motor 16 for rotating one ormore disks or platters 18 and an actuator assembly 20 for supporting oneor more head assemblies 22, wherein one or more of the head assemblies22 includes at least one read/write head 24 configured to write data toand/or read data from the disk 18.

The actuator assembly 20 includes a first actuator 26 and a secondactuator 28. The first actuator 26 is configured to rotate about a pivotbearing 30 to sweep and position the head assembly 22 across a surfaceof the disk 18. In particular, the first actuator 26 is configured tomove the head assembly 22 in both x- and y-directions relative to thedisk surface, as indicated by the three-dimensional Cartesian coordinatesystem in FIG. 1. The x- and y-directions correspond to the x-axis andy-axis of the coordinate system, respectively, and thus generally extendalong an x,y plane that is substantially parallel to the surface of thedisk 18. Thus, in some embodiments, the first actuator 26 may include,for example, a conventional rotary arm actuator configured to move thehead assembly 22 radially with respect to the axis of rotation of thedisk 18 in order swing the head 24 in arcuate paths across themagnetically encoded tracks of the disk 18. The first actuator 26 mayoperate generally as a result of input from a motor 32 (e.g., a voicecoil motor or the like). In other embodiments, the first actuator 26 mayinclude a belt and pulley arrangement, such as those arrangementsdescribed in U.S. Pat. Nos. 9,058,825, 9,190,087, 9,293,163, as well aspending U.S. patent application Ser. No. 15/043,095, the contents ofeach of which are hereby incorporated by reference herein in theirentireties.

The actuator assembly 26 includes an arm 34 rotatably coupled to thepivot bearing 32, wherein the second actuator 28 is coupled to thesupport arm 34. The second actuator 28 is configured to support the headassembly 22 and further move the read/write head 24 in a directionsubstantially orthogonal relative to the surface of the disk 18. Inparticular, the second actuator 28 is configured to move the read/writehead 24 in a z-direction towards or away from the disk surface. Thez-direction corresponds to the z-axis (shown in the coordinate system)that is orthogonal to the surface of the disk 18. In particular, thez-axis corresponds to the axis of rotation of the disk 18. Accordingly,the second actuator 28 will be referred to as the “z-axis actuator 28”in the following description. As will be described in greater detailherein, the z-axis actuator 28 of the present invention may includedifferent embodiments, such as a buckling arm design (shown in FIGS.4A-4B, 5A-5B) or a bending arm design (shown in FIGS. 8A and 8B), eachof which are configured to achieve movement of the read/write head 24 ina z-direction with precision and accuracy. As will be described ingreater detail herein, the z-axis actuator 28 is configured tocommunicate with a controller and, in response to control signals fromthe controller, move the read/write head so as to maintain theread/write head a desired distance from the disk surface.

FIG. 2 is a block diagram illustrating a system consistent with thepresent disclosure and configured to be incorporated into the HDD 10. Asshown, the system generally includes a disk 18 having a magnetic datarecording and reading surface. In some embodiments, the disk surface maybe bare. In other words, the disk surface may be devoid of any overcoator lubricant layers. The system further includes at least a read/writehead 24 having a magnetic transducer, wherein, in some embodiments, themagnetic transducer may be bare (i.e., the magnetic transducer is devoidof any overcoat or lubricant layers). It should be noted, however, thatin some embodiments, either the disk surface of the magnetic transducer,or both, may include a significantly small amount of hard coating orlubrication layer (i.e., a coating or layer having a thickness in therange of 0.1 nm to 2.0 nm). In some embodiments, at least one of thedisk surface and magnetic transducer may include a single layer ofgraphene, for example, which may have a thickness of approximately 0.35nm to 1.0 nm.

The magnetic transducer is configured to read data from or write data tothe magnetic surface of the disk 18. The system further includes az-axis actuator 28 coupled to the read/write head 24 and configured tocontrol movement of the read/write head 24 in a substantially orthogonaldirection relative to the surface of the disk 18. The system furtherincludes a controller 36 in electrical communication with the z-axisactuator 28 and configured to monitor positioning of the read/write head24 relative to the disk surface during rotation of the disk 18. Thecontroller is configured to cause the z-axis actuator 28 to adjust aposition of the read/write head 24 to prevent head-media spacing (HMS)between the magnetic transducer and the magnetic data recording andreading surface from falling outside of a desired range of HMS values.In other words, the controller is configured to monitor the HMS betweenthe read/write head 24 relative to the disk surface and transmit controlsignals to the z-axis actuator 28 to cause movement of the read/writehead 24 in the event that the read/write head is positioned outside of aset range of HMS values. Thus, the controller 36 may be referred toherein as a “servo controller 36”, in that the controller is aservomechanism utilizing error-sensing negative feedback to correct theperformance of a mechanism (e.g., adjust the position of the read/writehead 24).

In particular, the servo controller 36 may be configured to receive andprocess measurement data from a sensor 38, wherein the measurement datamay include one or more measurements of a flying height of theread/write head 24 relative to the disk surface during disk rotation. Inparticular, the sensor 38 may be configured to measure the distancebetween the magnetic transducer and the disk surface (e.g., the HMSmeasurements) and provide such measurements to the servo controller 36to be processed. In some embodiments, the sensor 38 includes acapacitive coupling device. In some embodiments, the read/write head 24is configured to measure the distance between the magnetic transducerand the disk surface via a capacitive coupling arrangement between theread/write head 24 and the disk surface. The measurement data may beobtained via measuring capacitive coupling between the read/write headand the disk surface and/or by comparing the amplitude of differentharmonic read signals generated from known servo patterns, or even fromrandom user data, for example.

The sensor 38 is then configured to transmit the measurement data to theservo controller 36. In turn, the servo controller 36 is configured toprocess the measurement data to determine the position of the read/writehead and to further determine whether the read/write head 24,specifically the magnetic transducer, falls outside of a set range ofHMS values.

In some embodiments, the set range of HMS values may be from 1.0 nm to10.0 nm. Accordingly, in the event that the magnetic transducer fallsoutside of the 1.0 nm to 10.0 nm range, the servo controller 36 isconfigured to generate and transmit a control signal to the z-axisactuator 28 to thereby cause the actuator 28 to move the read/write head24 to a position such that the magnetic transducer falls within the 1.0nm to 10.0 nm range. In some embodiments, the range of HMS values may benarrower, such as from 4.0 nm to 8.0 nm. Yet further still, in someembodiments, the HMS value may be set to approximately 4.3 nm. Thus, theservo controller 36 is configured to monitor the read/write head 24position during operation of the HDD and generate and transmit one ormore control signals causing the z-axis actuator 28 to move theread/write head 24, if necessary, so as to maintain a position of themagnetic transducer within the set HMS 4.3 nm value. Accordingly, thesystem of the present disclosure is configured to actively control theflying height of the head above the disk surface at all times, therebyensuring that the head remains within a desired HMS range duringoperation while also ensuring that the head never makes contact with thedisk surface.

As previously described, the system of the present disclosure does notrely on an ABS design. Accordingly, air within the HDD 10 is no longerrequired as the z-axis actuator 28 design of the present invention doesnot rely on aerodynamic forces to maintain the flying height of thehead. Accordingly, a low air pressure environment, including a zero, ornear-zero, air pressure may be maintained within the HDD 10 enclosure,thereby eliminating substantially all aerodynamic drag and turbulencethat are major causes of head and disk surface contact, disk flutter,TMR, and power consumption. However, in some embodiments, it may beadvantageous to maintain a low, but non-zero, air pressure within theHDD enclosure so as to aid in heat transfer between the differentcomponents of the HDD 10.

In order to maintain a low, near-zero, or zero air pressure environment,the chassis 12 and cover 14 of the HDD 10 may be hermetically sealed toone another via any known technique (e.g., adhesive, polymer strip orgasket, etc.). The hermetic seal will generally prevent atmospheric airfrom leaking back into the enclosure. However, the system may furtherinclude a vacuum pump 40, for example, configured to maintain thedesired low air pressure despite any leaks within the HDD enclosure.

Additionally, or alternatively, in some embodiments, any oxygenremaining within the HDD enclosure may be purged and replaced with aninert gas, such as nitrogen or helium, which may improve the longevityand operation of components within the HDD enclosure. For example,typical HDDs may include oxygen within the enclosure, which can lead tooxidation of the HDD components which may affect performance andreliability. Accordingly, purging the HDD enclosure of oxygen andreplacing with an inert gas prevent HDD components from being exposed tooxygen.

FIG. 3 is a flow diagram illustrating one embodiment of a method 300 formonitoring and actively controlling the position of a read/write headrelative to a disk surface using a system consistent with the presentdisclosure. The method 300 includes setting the HMS to an acceptablerange (operation 304). For example, the servo controller 36 may be usedto set a desired range of HMS values in which the read/write head 24 isto remain. The range of HMS values may include 1.0 nm to 10.0 nm, and,more particularly, from 4.0 nm to 8.0 nm. In some embodiments, anapproximate HMS value may be set, such as, for example, 4.3 nm. Themethod 300 further includes obtaining one or more HMS measurements(operation 306). As previously described, the system may include sensor38 configured to collect HMS measurements (e.g., measurements of thedistance between the magnetic transducer and the disk surface) via acapacitive coupling device. In alternative embodiments, the read/writehead 24 may be configured to measure the distance between the magnetictransducer and the disk surface via a capacitive coupling arrangement.

A determination may then be made in operation 308 as to whether the HMSmeasurement falls within the set range of (or approximate) HMS values.At this point, the servo controller is configured to process the HMSmeasurement data and, based on a comparison of the HMS measurement datawith the set range of (or approximate) HMS values, determine whether themagnetic transducer of the read/write head 24 is positioned accordingly.If it is determined in operation 308 that the magnetic transducer of theread/write head 24 is positioned within the set range of HMS values,then system continues to obtain measurement data (operation 306).However, if it is determined in operation 308 that the magnetictransducer of the read/write head 24 is positioned outside of the setrange of HMS values, then servo controller is configured to determinethe appropriate correction required, specifically calculating a z-axisposition error signal (operation 310). For example, the servo controllermay be configured to calculate an exact distance that the head must bemoved so as to fall back within the set range of HMS values.

The servo controller is then configured to generate a control signal forcontrolling operation of the z-axis actuator (operation 312) to causemovement of the head to a corrected position so as to place the magnetictransducer back within the set range of HMS values (operation 314). Forexample, if it is determined that the magnetic transducer is positionedbelow the minimum value of the HMS range (e.g., below 1.0 nm), then thecontrol signal causes the z-axis actuator to move of the read/write headin direction away from the disk surface to position the magnetictransducer within the HMS range. Similarly, if it is determined that themagnetic transducer is positioned above the maximum value of the HMSrange (e.g., above 10.0 nm), the control signal causes the z-axisactuator to move the read/write head in direction towards the disksurface to position the magnetic transducer within the HMS range. Uponadjusting the head, then system continues to obtain measurement data(operation 306).

It should be noted that the servo controller 36 is configured to monitorand actively control the position of a read/write head 24 relative tothe disk surface in a continual manner. In particular, the servocontroller 36 may be configured to receive and process HMS measurementdata periodically, such as at a relatively high frequency over a givenperiod of time. In some embodiments, the servo controller 36 may beconfigured to operate (i.e., monitor and control read/write head 24position) at 10 kilohertz (10,000 times per second).

While FIG. 3 illustrates method operations according variousembodiments, it is to be understood that in any embodiment not all ofthese operations are necessary. Indeed, it is fully contemplated hereinthat in other embodiments of the present disclosure, the operationsdepicted in FIG. 3 may be combined in a manner not specifically shown inany of the drawings, but still fully consistent with the presentdisclosure. Thus, claims directed to features and/or operations that arenot exactly shown in one drawing are deemed within the scope and contentof the present disclosure.

Additionally, operations for the embodiments have been further describedwith reference to the above figures and accompanying examples. Some ofthe figures may include a logic flow. Although such figures presentedherein may include a particular logic flow, it can be appreciated thatthe logic flow merely provides an example of how the generalfunctionality described herein can be implemented. Further, the givenlogic flow does not necessarily have to be executed in the orderpresented unless otherwise indicated. In addition, the given logic flowmay be implemented by a hardware element, a software element executed bya processor, or any combination thereof. The embodiments are not limitedto this context.

One of the advantages of eliminating the ABS design relates to the factthat the read/write head 24 does not require an air bearing slider,which can be the single-most expensive component of an HDD due to thetime-intensive manufacturing processes and costs involved. Air bearingsliders are generally made from aluminum oxide/titanium carbide(Al₂O₃/TiC), as this material is ideal for making sliders with smoothfaces and sharp edges. However, such material is incompatible with mostcommon semi-conductor manufacturing processes and, as a result, thesemanufacturing processes must be altered to accommodate the aluminumoxide/titanium carbide material, which is time intensive and results aloss of usable space on the substrate. For example, the process ofmanufacturing air bearing sliders may involve depositing a thin-filmmagnetic transducer, using a lithographic process, on a 200 mm diameterAl₂O₃/TiC wafer. The wafer is then partitioned into pieces that willeventually become the sliders (approximately 1 mm×0.8 mm×0.3 mm). Theprocess of cutting, polishing, and etching the air bearing sliders fromthe wafer includes numerous steps that are harsh and often suffer fromlow yield due to likely damage that occurs to the thin film transducers.Furthermore, much of the real-estate on the wafer is lost to the cuttingblades since the wafers cannot be thinned to less than 1 mm (the lengthof a single slider).

In some embodiments, the read/write head 24 may include a silicon (Si)substrate configured for supporting the magnetic transducer. The systemof the present invention allows for the manufacture of heads using a Sisubstrate from a Si wafer, wherein such a material is much morecompatible with most common semi-conductor manufacturing processes andequipment. The system of the present disclosure allows for large gainsin magnetic head manufacturing efficiencies to be obtained by reducingthe size of the head and increasing the number of heads that can beproduced on any given Si substrate in that the Si wafer has a size ofapproximately 300 mm, which is much greater than a typical 200 mm sizeof an Al₂O₃/TiC wafer. Thus, the larger 300 mm Si wafers can hold a lotmore magnetic transducer heads, which can be made even smaller than aslider face. In fact, since the transducer is approximately half amicron in size, the only lower limit on it size is that imposed by thedexterity of the automated handling machinery. Furthermore, prior tocutting, the Si wafer can be thinned for easier cutting and in order tominimize the amount of surface lost to the cutting blade. Accordingly,the process of manufacturing a head on a Si substrate is much moreefficient than manufacturing of air bearing sliders. The larger 300 mmSi wafers have much greater surface area than the 200 mm Al₂O₃/TiCwafers. Furthermore, the thin film heads have a smaller foot print thana slider face, and can therefore be packed much more tightly on asubstrate. Additionally, a standardized packaging process will havevirtually no yield losses with the Si substrate, in contrast to the airbearing slider shaping process.

The Si substrate may be configured to support one or more activeelectronic components configured to be coupled to, or in communicationwith, the magnetic transducer. For example, in one embodiment, the oneor more active electronic components may include a pre-amplifierpositioned on the Si substrate and in communication with a read elementof the magnetic transducer. The pre-amplifier is configured to amplifyread signals from the read element of the magnetic transducer so as toboost the read signal prior to transmission of the signal over a longerdistance. The advantage of including a pre-amplifier adjacent to theread element is that the read element can be a simple inductive elementinstead of a complex GMR sensor, which would greatly simplify themanufacturing of the magnetic transducer. Additionally, oralternatively, the Si substrate may include a sensor for measuring theHMS, such as, for example, a capacitive coupling circuit. Additionally,or alternative, the one or more active electronic components on the Sisubstrate may include one or more portions of the servo controlleritself. Other possible circuits that can be integrated with the magnetictransducer include, but not limited to, timing circuitry and buffermemory.

As previously described, the z-axis actuator 28 of the present inventionmay include different embodiments, such as a buckling arm design (shownin FIGS. 4A-4B, 5A-5B) or a bending arm design (shown in FIGS. 8A and8B), each of which are configured to achieve movement of the read/writehead 24 in a z-direction with precision and accuracy.

FIGS. 4A and 4B are perspective and side views of one embodiment of az-axis actuator assembly 400 having the buckling arm design and furtherillustrating a portion of a head assembly in a substantially planarconfiguration. The actuator 400 generally includes a rigid frame havingan elongate body 402 having a first end 404, an opposing second end 406,and a channel extending between the first and second ends 408. Theactuator assembly 400 further includes a head assembly positioned withinthe rigid frame and configured to control the flying height of themagnetic transducer of the read/write head relative to the disk surfaceduring disk rotation.

The head assembly generally includes an electromechanical member 410 anda suspension arm 412. The electromechanical member 410 is positionedwithin the channel 408 and adjacent to the first end 404 of the elongatebody of the frame. The suspension arm 412 is positioned within thechannel 408 between the electromechanical member 410 and the second end406 of the elongate body 402 of the frame. The electromechanical member410 is configured to receive the control signal from the servocontroller 36 to cause the electromechanical member 410 to contract andexpand along a length of the channel 408. For example, theelectromechanical member 410 may include a piezoelectric element.Accordingly, the control signal may include an electrical current inwhich the electromechanical member 410 expands. Thus, theelectromechanical member 410 generally has a first length L₁, and, uponreceiving a control signal including an electrical current, may thenexpand to a second length L₂ (see FIGS. 5A and 5B) greater than thefirst length L₁.

The suspension arm 412 includes a deformable portion 415 configured totransition between a substantially planar configuration (shown in FIGS.4A and 4B) and a buckled configuration (shown in FIGS. 5A and 5B) inresponse to associated contraction and expansion of the adjacentelectromechanical member 410. For example, as shown in FIGS. 5A and 5B,when in the buckled configuration, the deformable portion 414 extends ina direction away from the remainder of the suspension arm 412. As shown,a read/write head 416 is coupled to the deformable portion 414.Accordingly, contraction and expansion of the electromechanical member410, which results in movement the deformable portion 414, furtherresults in associated movement of the read/write head 416 coupled to thedeformable portion 414.

The suspension arm 412 further includes a plurality of notches 418across a width of the suspension arm 412 and along a length thereof. Theplurality of notches 418 are arranged in such as manner so as to allowportions of the suspension arm 412 to bend relative to one another. Forexample, the notches are arranged so as to allow the deformable portion414 to only buckle in an outward direction upon the application of thelinear force applied thereto from the electromechanical member 410 uponexpansion of the electromechanical member 410. The notches 418 mayfurther be arranged so as to prevent the deformable portion 414 frombuckling in an inward direction upon application of the linear forceapplied thereto from the expansion of the electromechanical member 410.

As shown in FIG. 4B, when the deformable portion is in the substantiallyplanar configuration, the read/write head 416 is a first HMS distance(HMS₁) from a disk surface. However, upon expansion of theelectromechanical member 410 in response to a control signal from theservo controller 36, the electromechanical may transition from the firstlength L₁ to the second length L₂ and apply a force against thesuspension arm 412, resulting in transitioning of the deformable portion414 from the planar configuration to the buckled configuration. Whentransitioning to the buckled configuration, as shown in FIG. 5B, theread/write head 416 moves in a substantially orthogonal direction awayfrom the suspension arm 412 and the frame and towards the data readingand recording surface of the disk 18 (as indicated by arrow 418),thereby resulting in a second HMS distance HMS₂ from the disk surface,which is less than the first HMS distance HMS₁. In other words,expansion of the electromechanical member 410 results in reduction inthe HMS between the read/write head 416 and disk surface.

The deformable portion 414 is further configured to return to thedefault planar configuration upon removable of the linear force to thesuspension arm 412. In other words, upon contraction of theelectromechanical member 410, the linear force from theelectromechanical member 410 against the suspension arm 412 is lessened,resulting in the deformable portion 414 returning to the planarconfiguration. Accordingly, upon transition of the deformable portion414 from the buckled configuration to the planar configuration, theread/write head 416 is configured to move in a substantially orthogonaldirection away from the data reading and recording surface of the disk18 and back towards the suspension arm 412 and frame. In other words,contraction of the electromechanical member 410 results in an increasein the HMS between the read/write head 416 and disk surface.Accordingly, the buckling arm actuator assembly 400 of FIGS. 4A-4B and5A-5B allows for a fully active control of read/write head movement in az-direction relative to the disk surface with precision and control viathe servo controller.

The amount of movement in the z-axis required for the actuator tomaintain the desired “flying” height may be equal to the z spacingtolerances between the platters and the planar (x, y) actuatorsupporting the z-axis actuator, which are a fixed amount, plus anyrun-time flutter in the platters and any axial runout in the fluiddynamic thrust bearing of the spindle motor, which are time varying.Reasonable fabrication and assembly tolerances are in the range of 0.02mm, while disk fluttering values, in a vacuum, are estimated to be +/−2micro-meters. The FDB thrust bearing typically contributes severalmicro-meters of runout albeit at a very low frequency. In someembodiments, the manufacturing tolerances, as well as any slack in thez-actuator head assembly, can be compensated for by the heating of thesuspension arms. For example, the suspension arm 412 may be coupled to aheating element (e.g., conductive filament or the like) configured toreceive an electrical current and, in turn, apply heat to the suspensionarm 412. Upon receiving heat, the suspension arm 412 may expand withinthe channel 408 and cause the deformable portion 414 to furthertransition to the buckled configuration to make up for any slack betweenthe electromechanical member 410 and suspension arm 412 and furtheradvance the deformable portion 414, and thus the read/write head 416, toa position closer to the disk surface. The disk flutter is compensatedfor in part by the piezo actuation as well as the conventional thermalflying height control of the magnetic transducer.

FIG. 6 is a side view of an assembly including the head assembly ofFIGS. 4A and 4B in a dual-design configuration. FIG. 7 is a side view ofthe dual-design configuration head assembly of FIG. 6 positioned betweentwo adjacent disks and illustrating one of the head assemblies in abuckled configuration. As shown, the dual-head design includes first andsecond z-axis actuator assemblies 400(1) and 400(2) positionedsubstantially parallel with one another but configured to buckle inopposing directions. This dual-head design is particularly advantageousfor placement in between two adjacent disks so as to allow the datareading and recording on associated opposing disk surfaces relative tothe first and second read/write heads. For example, as shown in FIG. 7,the second assembly 400(2) is in the buckled configuration, while thefirst assembly 400(1) remains in the planar configuration. However, itshould be noted that both assemblies 400(1) and 400(2) may operatesimultaneously in either of the planar or buckled configurations.

FIGS. 8A and 8B are side views of the bending arm design of a z-axisactuator assembly 500 compatible with the system of the presentdisclosure. As shown, the assembly 500 includes a rigid frame includingan elongate body 502 having a first end 504, an opposing second end 506,and a channel along a length thereof 508. The assembly 500 furtherincludes an electromechanical member 510 positioned within the channel508 and adjacent to the first end 504 of the elongate body 502. Similarto electromechanical member 410 previously described herein, theelectromechanical member 510 is configured to receive a control signalfrom the servo controller 36 so as to cause the electromechanical member510 to contract and expand along a length of the channel 508, therebychanging a length of the electromechanical member 510 (e.g., transitionbetween a first length L₁ and a second length L₂ greater than the firstlength L₁).

The assembly 500 further includes an L-shaped suspension arm 512 havinga short segment 514 and a long segment 516. The short segment 514 isdirectly coupled to a portion of the frame and positioned adjacent tothe electromechanical member 510 at a notched portion 517. The longsegment 516 includes a distal-most end 518 to which a read/write head520 is coupled. The suspension arm 512 is configured to transitionbetween a substantially planar configuration (shown in FIG. 8A) and abent configuration (shown in FIG. 8B) in response to associatedcontraction and expansion of the adjacent electromechanical member 510.In particular, upon expanding (e.g., increasing from the first length L₁to the second length L₂), the electromechanical member 510 is configuredto apply a linear force against the short segment 514 of the suspensionarm 512, which results in bending of the suspension arm 512 at thenotched portion 517 (which serves as the axis of rotation). The notchedportion 517 may be arranged so as to allow the suspension arm 512 toonly bend in an outward direction upon linear force applied thereto fromthe electromechanical member 510 when electromechanical member 510expands. The notched portion 517 may further be arranged so as toprevent the suspension arm 512 from bending in an inward direction uponthe application of linear force from the electromechanical member 510when electromechanical member 510 expands.

When transitioning from the planar configuration to the bentconfiguration, the distal-most end 518 of the suspension arm 512 has themost dramatic amount of movement in a direction away from the frame. Inturn, the read/write head 520 attached to the distal-most end 518 movesin a direction towards the data reading and recording surface of thedisk 418, thereby decreasing the HMS distance between the read/writehead 520 and disk surface.

The suspension arm 512 is further configured to return to the defaultplanar configuration upon removable of the linear force to the shortsegment 514 from the electromechanical member 510. In other words, uponcontraction of the electromechanical member 510, the linear force fromthe electromechanical member 510 against the short segment 514 islessened, resulting in the suspension arm 512 bending in a directionaway from the disk surface and returning to the planar configuration viathe notched portion 517. Accordingly, upon transition of the suspensionarm 512 from the bent configuration to the planar configuration, theread/write head 520 is configured to move in a direction away from thedata reading and recording surface of the disk 18. In other words,contraction of the electromechanical member 510 results in an increasein the HMS between the read/write head 520 and disk surface.

As used in any embodiment herein, the term “module” may refer tosoftware, firmware and/or circuitry configured to perform any of theaforementioned operations. Software may be embodied as a softwarepackage, code, instructions, instruction sets and/or data recorded onnon-transitory computer readable storage medium. Firmware may beembodied as code, instructions or instruction sets and/or data that arehard-coded (e.g., nonvolatile) in memory devices. “Circuitry”, as usedin any embodiment herein, may comprise, for example, singly or in anycombination, hardwired circuitry, programmable circuitry such ascomputer processors comprising one or more individual instructionprocessing cores, state machine circuitry, and/or firmware that storesinstructions executed by programmable circuitry. The modules may,collectively or individually, be embodied as circuitry that forms partof a larger system, for example, an integrated circuit (IC), systemon-chip (SoC), desktop computers, laptop computers, tablet computers,servers, smart phones, etc.

Any of the operations described herein may be implemented in a systemthat includes one or more storage mediums having stored thereon,individually or in combination, instructions that when executed by oneor more processors perform the methods. Here, the processor may include,for example, a server CPU, a mobile device CPU, and/or otherprogrammable circuitry.

Also, it is intended that operations described herein may be distributedacross a plurality of physical devices, such as processing structures atmore than one different physical location. The storage medium mayinclude any type of tangible medium, for example, any type of diskincluding hard disks, floppy disks, optical disks, compact diskread-only memories (CD-ROMs), compact disk rewritables (CD-RWs), andmagneto-optical disks, semiconductor devices such as read-only memories(ROMs), random access memories (RAMs) such as dynamic and static RAMs,erasable programmable read-only memories (EPROMs), electrically erasableprogrammable read-only memories (EEPROMs), flash memories, Solid StateDisks (SSDs), magnetic or optical cards, or any type of media suitablefor storing electronic instructions. Other embodiments may beimplemented as software modules executed by a programmable controldevice. The storage medium may be non-transitory.

As described herein, various embodiments may be implemented usinghardware elements, software elements, or any combination thereof.Examples of hardware elements may include processors, microprocessors,circuits, circuit elements (e.g., transistors, resistors, capacitors,inductors, and so forth), integrated circuits, application specificintegrated circuits (ASIC), programmable logic devices (PLD), digitalsignal processors (DSP), field programmable gate array (FPGA), logicgates, registers, semiconductor device, chips, microchips, chip sets,and so forth.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, appearances of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments.

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention,in the use of such terms and expressions, of excluding any equivalentsof the features shown and described (or portions thereof), and it isrecognized that various modifications are possible within the scope ofthe claims. Accordingly, the claims are intended to cover all suchequivalents.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patentapplications, patent publications, journals, books, papers, webcontents, have been made throughout this disclosure. All such documentsare hereby incorporated herein by reference in their entirety for allpurposes.

Equivalents

Various modifications of the invention and many further embodimentsthereof, in addition to those shown and described herein, will becomeapparent to those skilled in the art from the full contents of thisdocument, including references to the scientific and patent literaturecited herein. The subject matter herein contains important information,exemplification and guidance that can be adapted to the practice of thisinvention in its various embodiments and equivalents thereof.

1. A hard disk drive comprising: a disk comprising a magnetic datarecording and reading surface; a read/write head for reading data fromand writing data to the disk surface; a z-axis actuator coupled to thehead for controlling movement of the head in a substantially orthogonaldirection relative to the disk surface; and a controller for monitoringa distance of the head relative to the disk surface and for maintainingthe distance within a predetermined range; wherein one or both of thedisk surface and the head comprises a significantly small amount ofovercoat or lubricant layer.
 2. The hard disk drive of claim 1 whereinthe robust control actively controls the head within a tolerance ofbetween 1.0 nm and 10.0 nm.
 3. The hard disk drive of claim 1 whereinthe robust control comprises monitoring head-media spacing (HMS) betweenthe head and the disk surface and also transmitting signals to thez-axis actuator to cause movement of the head.
 4. The hard disk drive ofclaim 1 wherein the robust control comprises a servomechanism witherror-sensing negative feedback to maintain the head within a range of1.0 nm and 10.0 nm.
 5. The hard disk drive of claim 1 wherein the z-axisactuator is rigidly coupled to the head. 6-25. (canceled)
 26. The harddisk drive of claim 1 wherein the overcoat or lubricant layer has athickness of between 0.1 nm and 2.0 nm.
 27. The hard disk drive of claim1 wherein the overcoat or lubricant layer has a thickness of between0.35 nm and 1.0 nm.